A study on mechanism of sapphire polishing using the diamond abrasive by molecular dynamics

Polished sapphire has been widely used because of its superior mechanical and physical characteristics. However, the polishing process of sapphire is still unclear and the processing effects need to be improved. Therefore, the polishing process of sapphire with diamond abrasive particles was studied by molecular dynamics method. The behavior of diamond removing sapphire material in polishing process was researched. The effects of the polishing speed, depth, and the abrasive size were investigated in the aspects of polishing force, surface topography, subsurface damage, removed atoms, temperature distribution and average friction coefficient. The outcomes indicated that the surface temperature of sapphire was higher with the rising polishing velocity, but the subsurface defect of sapphire was deeper. Larger indentation depths resulted in higher forces and temperatures, deeper grooves, more removed atoms and bigger average friction coefficients, but poor polished subsurface. Bigger abrasives gained lower friction coefficients and higher numbers of removed atoms. It was found that both good polishing efficiency and quality are obtained under the speed 150 m/s, the polishing depth 15 Å and the abrasive particle radius 20 Å. This study is helpful to improving the sapphire polishing effects and understanding its polishing process.